1. Field
The present disclosure relates generally to methods and apparatus for initial acquisition gain control in a communication system and, more particularly, to methods and apparatus for adjusting the gain of a transceiver when receiving initial acquisition symbols in a wireless communication system to prevent overshoot due to incorrect gain settings.
2. Background
In particular communication systems such as orthogonal frequency division multiplexing (OFDM) communication systems, it is known to transmit one or more specific OFDM symbols for use in assisting a receiver portion of a transceiver in initial timing and frequency acquisition. The one or more specific OFDM symbols, which are acquisition pilot symbols, are repeatedly transmitted at a full or maximal power value at a fixed time interval. The receiver portion of a transceiver uses the symbols to obtain initial timing and frequency acquisition, such as when the transceiver is powered up or wakes up from a sleep mode.
In typical transceivers, however, gain control such as automatic gain control (AGC), is used to set a gain of the receiver portion based on the measured power of the received symbol. In certain situations an OFDM symbol may precede the acquisition pilot symbol or symbols and may not be transmitted at full power, such as in the case where the preceding OFDM symbol is only partially loaded with data. In such a case, the gain setting of the gain control may be set in a range too high to properly resolve the next OFDM acquisition pilot symbol transmitted at full power, thus leading to overshoot or distortion of the signal amplification. This leads to initial acquisition failure, degrading the performance of the receiver portion of the transceiver.